Technical Field
[0001] The present invention relates to a method for identifying the origin or kind of a
separator that allows users to easily identify the origin or kind of the separator
itself or an electrochemical device using the same separator.
Background Art
[0002] Electrochemical devices are power sources for electronic appliances, etc. As the
use of batteries is enlarged to applications for the storage of energy for portable
telephones, camcorders, notebook computers, personal computers and electric vehicles,
efforts on the research and development of batteries are increasingly embodied.
[0003] Meanwhile, since the electrochemical devices have been in increasing demand, counterfeits
thereof have been distributed more and more. Such counterfeits have much lower safety
than authentic products. Therefore, there has been an imminent need for a method for
checking the authenticity of an electrochemical device.
[0004] According to the prior art, there has been suggested a method for checking the authenticity
of an electrochemical device by incorporating a semiconductor capable of communicating
with the main body of an electronic appliance into the electrochemical device. However,
the above method requires an additional space for housing the semiconductor inside
the device, so that the space for receiving electrodes inside the device grows smaller.
This ultimately results in a drop in the capacity of a battery. Additionally, such
introduction of a semiconductor into the electrochemical device causes degradation
of the productivity and cost-efficiency.
[0005] WO 2006/068428 A1 discloses a separator including inorganic particles and a lithium secondary battery
comprising the same.
Disclosure
Technical Problem
[0006] Therefore, the present invention has been made in view of the above-mentioned problems.
It is an object of the present invention to provide a method for identifying the origin
or kind of a separator which inorganic particle(s) having a unique spectrum or color
pattern is(are) introduced according to a predetermined rule, so that the separator
is identifiable and the separator or an electrochemical device using the same allows
users to identify its origin or kind.
Technical solution
[0007] In order to achieve the above-mentioned object, there is provided a method for identifying
the origin or kind of the separator itself or the electrochemical device comprising
the same by using a separator.
[0008] An electrochemical device includes an anode, a cathode, a separator, and an electrolyte.
Herein, the separator can prevent electric contact of the anode and the cathode while
allowing ions to pass through the separator. As a separator a
polyolefin-based or non-woven-based porous substrate having no color or a pale yellow
color has been mainly used. There has been no case where a separator was used to identify
the origin or kind of the separator itself or an electrochemical device.
[0009] According to the present invention, inorganic particle(s) having a unique spectrum
or color pattern is(are) introduced into the separator according to a predetermined
rule, so as to make the separator itself identifiable.
[0010] Each kind of inorganic particle has its unique spectrum or color pattern. Therefore,
when such inorganic particle(s) is(are) introduced into a separator according to a
predetermined rule, the separator comprising the inorganic particle(s) can be identifiable
like a trademark.
[0011] Herein, the above "predetermined rule" means a specific spectrum (peak position and
intensity) and/or color pattern determined preliminarily so that the separator can
be distinguished from the others manufactured by a third party. Particularly, the
specific spectrum (peak position and intensity) and/or color pattern may be variable
depending on the number, kind, content, etc. of the inorganic particles used in the
separator. For example, it is possible to control the peak position and intensity
by using one or more kinds of inorganic particles having a unique spectrum or color
pattern and by adjusting the amounts of the particles. Otherwise, it is possible to
control the color pattern by using one or more kinds of inorganic particles having
a unique spectrum or color pattern in the visible light or non-visible light range;
or one or more kinds of inorganic particles having a unique spectrum or color pattern
under a specific chemical condition (e.g. temperature, oxidation state, etc.). Further,
it is possible to control both the spectrum and the color pattern by using at least
two kinds of the aforementioned inorganic particles in combination or by varying the
arrangement of the particles.
[0012] Therefore, according to the present invention, it is possible to identify the origin
or kind of the separator itself or the electrochemical device comprising the same
by checking the spectrum and/or color pattern of the separator. Particularly, according
to the present invention, the separator itself functions as a means for identification.
Thus, no additional space for an identification means is required, thereby preventing
a drop in the capacity of the electrochemical device. Also, the identification method
according to the present invention may be applied to counterfeits made only inside
the electrochemical device.
[0013] There is no particular limitation in the inorganic particle used in the present invention,
as long as the particle has its unique spectrum or color pattern.
[0014] For example, the inorganic particle includes: (i) inorganic particles having a unique
spectrum or color pattern in the visible light range; (ii) inorganic particles having
a unique spectrum or color pattern in the non-visible light range; or (iii) inorganic
particles having a unique spectrum or color pattern under a specific chemical condition
(e.g. temperature or oxidation state). In addition, inorganic particles having a unique
spectrum or color pattern through coloring belong to a scope of the present invention.
In this case, the coloring may be achieved through a surface treatment by dye having
a unique spectrum or color pattern. Also, inorganic particles used in paints or pigments,
or phosphor particles used in display devices or lamps may be used in the present
invention.
[0015] Non-limiting examples of the inorganic particle having a unique spectrum or color
pattern, such as a white, black, yellow, orange, brown, red, violet, blue, green,
gray, pink or fluorescent color, in the visible light range (a wavelength range of
380∼770nm) are as follows:
- (a) white: Al2O3, ZnO, ZnS, SiO2, ZrO2, SnO2, CeO2, MgO, CaO, Y2O3, TiO2, Sb2O3, BaTiO3, SrTiO3, Pb(Zr,Ti)O3 (PZT), Pb1-xLaxZr1-yTiyO3 (PLZT), etc.
- (b) black: Fe3O4, (Co, Ni)O-(Cr, Fe)2O3, etc.
- (c) yellow: PbCrO4, ZnCr04, BaCrO4, CdS, FeO(OH) nH2O, TiO2-NiO-Sb2O3, Pb(CN)2, Ca2PbO4, Al,Fe,Sn-2PbO-Sb2O5, V-SnO2, V-ZrO2, Pr-ZrSiO4, CrSbO4 or Cr2WO6-TiO2, ZrSO4 coated CdS or (CdZn)S, etc.
- (d) orange: PbCrO4 PbO, PbCrO4 PbMoO4 PbSO4, etc.
- (e) brown: Fe2O3+FeO, Fe2O3+MnO2+Mn3O4, ZnO ·(Al, Cr, Fe)2O3, etc.
- (f) red: Fe2O3, Pb3O4, HgS, CdS+CdSe, CdS+HgS, 2Sb2S3 Sb2O3, etc.
- (g) violet: Co3(PO4)2, Co3(PO4)2 4H2O, Co3(PO4)2 8H2O, etc.
- (h) blue: 3NaAl SiO4 Na2S2, Fe4[Fe(CN6)3] nH2O, CoO nAl2O3, CoO nSnO2 mMgO(n=1.5∼3.5, m=2∼6), Co3O4+SiO2+Al2O3+Fe2O3+NiO+MnO, CoO-nAl2O3 or (Co, Zn)O-nAl2O3, 2(Co, Zn)O ·SiO2, V-ZrSiO4, etc.
- (i) green: Cr2O3, Cr2O(OH)4, Cu(CH3CO2)2 3CuO(AsO2)2, CoO-ZnO-MgO, (Co, Zn)O ·(Al, Cr)2O3, 3CaO-Cr2O3 ·3SiO2, (Al, Cr)2O3, etc.
- (j) gray: Sb-SnO2, Co, Ni-ZrSiO4, etc.
- (k) pink: Mn, P-α-Al2O3, ZnO ·(Al, Cr)2O3, Cr-CaO ·SnO2 ·SiO2, Fe-ZrSiO4, Cr,Co-CaO ·SnO2 ·SiO2, ZrSiO4 coated Cd(S,Se), etc.
- (l) fluorescent color: ZnS, Zn2SiO4, (Zn,Cd)S, CaS, SrS, CaWO4, etc.
- (m) others: SiC (green and/or black), Si3N4(white), etc.
[0016] In this case, it is preferred that the white inorganic particle(s) is(are) mixed
with other inorganic particles, so as to diversely adjust the spectrum and/or the
color patterns of the separator.
[0017] Although there is no particular limitation in the size of the inorganic particle,
the inorganic particle preferably has a size of 0.001
µm∼10
µm. If the size is less than 0.01
µm, the pores formed by the inorganic particles are too small. Thus, it may be difficult
to function sufficiently as a separator. If the size is greater than 10
µm, the resultant separator has an increased thickness. Thus, it may result in an increase
in the electrochemical device size or a decrease in the quantity of used electrode
active material, thereby causing decrease in the capacity of the electrochemical.
[0018] Meanwhile, the inorganic particles may be connected and fixed to each other by polymers.
Herein, for the polymer, binder polymers well-known in the art may be used. The polymer
serves as a binder that interconnects and stably fixes the inorganic particles among
themselves, and between the inorganic particles and the surface of an electrode substrate,
and thus prevents degradation in mechanical properties of a resultant separator.
[0019] The polymer preferably has a glass transition temperature (Tg) of between -200°C
and 200°C in order to improve mechanical properties such as flexibility and elasticity
of a final resultant separator.
[0020] Additionally, the polymer preferably shows a high degree of swelling with an electrolyte
by being gelled when impregnated with an electrolyte, and more preferably has a solubility
parameter between 15 and 45 MPa
1/2. This is because, when the solubility parameter of the polymers is out of the above-mentioned
range, it is difficult to swell the polymers with typical electrolyte for electrochemical
devices.
[0021] Non-limiting examples of the polymer that may be used in the present invention include
polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene,
polymethylmethacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate,
polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate
butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol,
cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxylmethyl cellulose, acrylonitrile-styrene-butadiene
copolymer, polyimide or mixtures thereof.
[0022] There is no particular limitation in the ratio of the inorganic particles to the
polymer when preparing the separator. The ratio may be controlled in a range of 10:90∼99:1
(on the weight basis), and preferably of 50:50∼99:1 (on the weight basis), depending
on the thickness and physical properties of the resultant separator and the content
of the inorganic particles defined by the predetermined rule.
[0023] The separator may further comprise other additives.
[0024] Meanwhile, the separator includes a porous structure formed due to the interstitial
volume between the inorganic particles. Herein, the pores may be formed with a size
of micrometer in a tangled configuration between inorganic particles; or between inorganic
particles and polymers or between polymers in the case where the polymers are used.
The porous structure can serve as a path for transfer and movement of lithium ions
when filled with subsequently injected electrolyte. Therefore, the pore size and the
porosity may significantly affect the adjustment of the ion conductivity of the separator.
For this reason, preferably, the pore size ranges from 0.001 to 10
µm and the porosity ranges from 5 to 95%, so as to have a sufficient room to be filled
with the electrolyte and improve the lithium ion conductivity of the separator. In
this case, the pore size and the porosity can be adjusted by the size of the inorganic
particle, or by a content ratio (I/P) of the inorganic particle (I) to the polymers
(P). For example, the larger the inorganic particles are, the larger the interstitial
distance between the inorganic particles is and the larger the pore size is. Moreover,
as the content ratio (I/P) of the inorganic particle (I) to the polymers (p) grows
higher, the porosity may increase.
[0025] Also, there is no particular limitation in the separator thickness, which can be
adjusted within a range of 1 to 100
µm in consideration of the battery performance.
[0026] The separator may be realized by two types of embodiments, but is not limited thereto.
<separator example 1>
[0027] According to one embodiment of the separator, the inorganic particle containing layer
is placed on at least one area selected from the group consisting of a surface of
a porous substrate and a porous part of the substrate. For example, the separator
may have a structure including a porous substrate and inorganic particles coated on
the substrate.
[0028] There is no particular limitation in the porous substrate, as long as it is a substrate
having pores. However, a heat resistant porous substrate having a melting point of
200°C or higher is preferred.
[0029] This is because the heat-resistant porous substrate can improve the thermal stability
of the separator and thus can prevent danger that may be caused by exterior and/or
interior heat stimulation.
[0030] Non-limiting examples of the porous substrate include high density polyethylene(HDPE),
low density polyethylene(LDPE), linear low density polyethylene(LLDPE), ultra high
molecular weight polyethylene(UHMW-PE), polyethylene terephthalate, polybutylene terephthalate,
polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetherether ketone,
polyether sulfone, polyphenylene oxide, polyphenylene sulfidro, polyethylene naphthalene
or mixtures thereof. Also, other heat resistant engineering plastics may be used with
no particular limitation.
[0031] Although there is no particular limitation in thickness of the porous substrate,
the porous substrate preferably has a thickness of between 1
µm and 100
µm, more preferably of between 5
µm and 50
µm. When the porous substrate has a thickness of less than 1
µm, it is difficult to maintain mechanical properties. When the porous substrate has
a thickness of greater than 100
µm, it may function as resistance layer of lithium ion.
[0032] Although there is no particular limitation in pore size and porosity of the porous
substrate, the porous substrate preferably has a porosity of between 5% and 95%. The
pore size (diameter) preferably ranges from 0.01
µm to 50
µm, more preferably from 0.1
µm to 20
µm. When the pore size and porosity are less than 0.01
µm and 5%, respectively, the porous substrate may function as resistance layer of lithium
ion. When the pore size and porosity are greater than 50
µm and 95%, respectively, it is difficult to maintain mechanical properties.
[0033] The porous substrate may take the form of a membrane or fiber. When the porous substrate
is fibrous, it may be a nonwoven web forming a porous web (preferably, spunbond type
web comprising long fibers or melt blown type web).
[0034] The separator may be manufactured by coating an inorganic particle(s) having a unique
spectrum or color pattern on at least one area selected from the group consisting
of a surface of the porous substrate and a porous part of the substrate. In this case,
it is preferred to form a specific pattern (for example, stripes, dots, etc.) on the
porous substrate, by coating the inorganic particle(s) on the entire surface, a portion
of the surface, or a portion of the porous part of the porous substrate.
[0035] One embodiment of the method for the above separator comprises the steps of: (i)
manufacturing an inorganic particle solution by dissolving the inorganic particles
into a solvent; and (ii) drying after coating the inorganic particle solution of step
(i) on at least one area selected from the group consisting of a surface of a porous
substrate and a porous part of the substrate.
[0036] In this case, in step (i), polymers capable of interconnecting and fixing the inorganic
particles or other additives may be additionally used.
[0037] Meanwhile, in step (i), although there is no particular limitation in the solvent,
the solvent preferably has a solubility parameter similar to that of the binder polymer
to be used and a low boiling point, so as to facilitate uniform mixing and removal
of the solvent. Non-limiting examples of the solvent that may be used include acetone,
tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone
(NMP), cyclohexane, water or mixtures thereof.
[0038] Also, in step (i), it is preferable to perform a step of pulverizing inorganic particles
after dissolving the inorganic particles into the solvent. The time needed for pulverization
is suitably 1-20 hours. The particle size of the pulverized particles ranges preferably
from 0.001 and 10
µm. Conventional pulverization methods (ex. ball mill, attrition mill) may be used.
[0039] And, in step (ii), the conventional coating methods known to one skilled in the art
may be used. It is possible to use various processes including dip coating, die coating,
roll coating, comma coating or combinations thereof.
[0040] Meanwhile, in order to coat the inorganic particles on the porous substrate, a sputtering
method, preferably a sputtering method using a screen may be used. Then, it is possible
to omit the step of dissolving inorganic particles into a solvent and removing the
solvent. Thus, it is possible to form a pattern on the porous substrate easily and
simply.
<separator example 2>
[0041] Another feature employs a freestanding structure in which inorganic particles themselves
can serve as supporters and spacers without a further supporter, such as the porous
substrate. According to this feature, the inorganic particles are physically interconnected
and fixed while forming a porous structure.
[0042] The separator can be manufactured according to a process including the steps of:
forming an inorganic particle-containing layer on a substrate (ex. Teflon sheet) according
to the same method as in <separator example 1>; and then detaching the substrate or
detaching the substrate and compressing.
[0043] Furthermore, an electrochemical device may comprise an anode, a cathode, a separator,
and an electrolyte. In this case, the separator includes the aforementioned separator.
[0044] The electrochemical device includes all types of devices in which electrochemical
reactions are performed. Particular examples of the electrochemical device include
all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors.
Examples of the secondary batteries include lithium metal secondary batteries, lithium
ion secondary batteries, lithium polymer secondary batteries or lithium ion polymer
secondary batteries.
[0045] The electrochemical device may be obtained by using a conventional method known to
those skilled in the art, except that the separator is the aforementioned separator.
For example, the method may comprise the steps of: (a) inserting the aforementioned
separator between the cathode and the anode to form an electrode assembly, and introducing
the electrode assembly into a casing for an electrochemical device; and (b) injecting
an electrolyte to the casing.
[0046] The electrolyte may be used a conventional electrolyte known to those skilled in
the art, and generally comprises an electrolyte salt and an electrolyte solvent. There
is no particular limitation in the electrolyte salt, as long as the salt is conventionally
used as an electrolyte salt for a nonaqueous electrolyte.
[0047] The electrolyte salt that may be used in the present invention includes a salt represented
by the formula of A
+B
-, wherein A
+ represents an alkali metal cation selected from the group consisting of Li
+, Na
+, K
+ and combinations thereof, and B
- represents an anion selected from the group consisting of PF
6-, BF
4-, Cl
-, Br
-, I
-, ClO
4-, AsF
6-, CH
3CO
3-, N(CF
3SO
2)
2-, C(CF
2SO
2)
3- and combinations thereof. A lithium salt is particularly preferred.
[0048] The electrolyte solvent that may be used in the present invention includes cyclic
carbonates, linear carbonates, lactone, ether, ester, sulfoxide, acetonitrile, lactam,
ketone, or the like. Non-limiting examples of the cyclic carbonates include ethylene
carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene
carbonate (FEC), or the like. Non-limiting examples of the linear carbonates include
diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), ethyl
methyl carbonate (EMC), methyl propyl carbonate (MPC), or the like. Non-limiting example
of the lactone includes gamma-butyrolactone (GBL), and Non-limiting examples of the
ether include dibutyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, 1,4-dioxane,
diethoxy ethane, dimethoxy ethane, or the like. Non-limiting examples of the ester
include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate,
propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate,
methyl pivalate, or the like. Also, example of the sulfoxide includes dimethyl sulfoxide
and example of the ketone includes poly methyl vinyl ketone. Halogen derivatives of
the above electrolyte solvents may also be used. The above electrolyte solvents may
be used alone or in combination.
[0049] The present invention provides a method for identifying the origin or kind of the
separator itself or the electrochemical device comprising the same by using the aforementioned
separator.
[0050] The aforementioned separator comprises the inorganic particle(s) having a unique
spectrum or color pattern according to a predetermined rule. Therefore, it is possible
to identify the origin or kind of the separator itself or the electrochemical device
comprising the same by using a sensor for observing a spectrum or color pattern (including
the naked eye and a conventional spectrometer such as a visible light spectrometer)
to check whether the spectrum or color pattern (e.g. color, brightness or saturation
under a specific wavelength or chemical condition) of the inorganic particle(s) introduced
into the separator conforms to the predetermined rule or not. In this manner, it is
possible to identify the authenticity of the separator or electrochemical device according
to the present invention. It is also possible to distinguish one type of separator
or electrochemical device from the others. Therefore, any separator or electrochemical
device can be prevented from being misused during a manufacturing process.
Brief Description of the Drawings
[0051]
FIG. 1 is photographs of separators manufactured according to Examples 1-6.
FIG. 2 is photographs of separators manufactured according to Examples of 2 and 7.
FIG. 3 is a photograph of a separator manufactured according to Example 8.
FIG. 4 is photographs of a polyolefin-based separator; and a non-woven -based separator.
FIG. 5 is the absorption spectra of the separators according to Examples 1∼6 and Comparative
Example 1.
Mode for Invention
[0052] Reference will now be made in detail to the preferred embodiments of the present
invention.
Example 1
1-1. Manufacture of Separator
[0053] About 5 parts by weight of a polyvinylidene fluoride-chlorotrifluoroethylene copolymer
(PVdF-CTFE copolymer) was added to 100 parts by weight of acetone and dissolved therein
at 50°C for about 12 hours or more to provide a polymer solution. To the preformed
polymer solution, a mixture containing inorganic particles showing a blue color in
the visible light region, CoAl
2O
4, and PVdF-CTFE in a weight ratio of 80:20 was added, and then the inorganic particles
were crushed and dispersed by using a ball mill for 12 hours or more to provide slurry.
In the slurry, the inorganic particles had a particle diameter of 400 nm.
[0054] Then, the slurry was coated onto the surface of the cathode and the anode obtained
as described above via a dip coating process, followed by drying, to provide a separator.
1-2.
Manufacture of Lithium Secondary Battery
(Manufacture of cathode)
[0055] To N-methyl-2-pyrrolidone (NMP) as a solvent, 94 wt% of LiCoO
2 as a cathode active material, 3 wt% of carbon black as a conductive agent and 3 wt%
of PVdF as a binder were added to form slurry for a cathode. The slurry was coated
on Al foil having a thickness of about 20
µm as a cathode collector, and then dried to form a cathode. Then, the cathode was
subjected to roll press.
(Manufacture of anode)
[0056] To NMP as a solvent, 96 wt% of carbon powder as an anode active material, 3 wt% of
polyvinylidene fluoride (PVdF) as a binder and 1 wt% of carbon black as a conductive
agent were added to form mixed slurry for an anode. The slurry was coated on Cu foil
having a thickness of about 10
µm as an anode collector, and then dried to form an anode. Then, the anode was subjected
to roll press.
(Manufacture of battery)
[0057] The cathode and anode obtained as described above were stacked with the separator
as described in Example 1-1 to form an assembly. Then, an electrolyte was injected
into the assembly to provide a secondary battery. The electrolyte contained 1M lithium
hexafluorophosphate (LiPF
6) dissolved in ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume
ratio of 1:2 (EC/EMC).
[Example 2]
[0058] A separator and a lithium secondary battery were provided in the same manner as described
in Example 1, except that inorganic particles showing a green color in the visible
light region, Cr
2O
3, were used instead of CoAl
2O
4.
[Example 3]
[0059] A separator and a lithium secondary battery were provided in the same manner as described
in Example 1, except that inorganic particles showing a red color in the visible light
region, Fe
2O
3, were used instead of CoAl
2O
4.
[Example 4]
[0060] A separator and a lithium secondary battery were provided in the same manner as described
in Example 1, except that inorganic particles showing a yellow color in the visible
light region, (Ti,Ni,Sb)O
2, were used instead of CoAl
2O
4.
[Example 5]
[0061] A separator and a lithium secondary battery were provided in the same manner as described
in Example 1, except that inorganic particles containing CoAl
2O
4 and Fe
2O
3 in a weight ratio of 33:67 were used instead of CoAl
2O
4.
[Example 6]
[0062] A separator and a lithium secondary battery were provided in the same manner as described
in Example 1, except that inorganic particles containing CoAl
2O
4 and Fe
2O
3 in a weight ratio of 67:33 were used instead of CoAl
2O
4.
[Example 7]
[0063] A separator and a lithium secondary battery were manufactured in the same manner
as in Example 1, except that Cr
2O
3 and Al
2O
3 were used instead of CoAl
2O
4 and the weight ratio of Cr
2O
3: Al
2O
3: PVdF was changed to 60:20:20, 30:50:20, and 10:70:20.
[Example 8]
[0064] A separator and a lithium secondary battery were provided in the same manner as described
in Example 1, except that SiC was used instead of CoAl
2O
4.
[Comparative Example 1]
[0065] A separator and a lithium secondary battery were provided in the same manner as described
in Example 1, except that inorganic particles showing a white color in the visible
light region, alumina (Al
2O
3), were used instead of CoAl
2O
4.
[Experimental Example]
[0066] The absorption spectra of the separators according to Examples 1∼6 and Comparative
Example 1 were observed by using a spectrometer. The results are shown in FIG. 5.
It can be seen from the experimental results that the separator introduced the inorganic
particle(s) shows a different spectrum depending on the kind and content of the inorganic
particle(s). Such a specific spectrum can function as a means for identifying the
separator itself or the electrochemical device using the same.
[0067] Meanwhile, FIGs. 1, 2, 3 and 4 show the photographic views of the separators according
to Examples 1∼8 and polyolefin-based separator, taken in the visible light range.
It can be seen from the above results that the separator can be identified sufficiently
with the naked eye.
Industrial Applicability
[0068] As can be seen from the foregoing, according to the present invention, it is possible
to identify the origin or kind of the separator itself or the electrochemical device
using the same separator without any modification or addition in the structure of
the device. Thus, it is possible to identify the authenticity of the separator or
electrochemical device according to the present invention. It is also possible to
distinguish one type of separator or electrochemical device from the others. Therefore,
any separator or electrochemical device can be prevented from being misused during
a manufacturing process.